I received this image the other day with a question about what causes the black line under veneer provisionals. There are obviously tissue issues here as well and for our purposes here we will focus on the black line.

That line is actually an accumulation and proliferation of a bacteroides strain, an anaerobic bacteria that will stain dentin. It is a common contaminant in the mouth and will grow quickly under provisionals if they are not well sealed and if the tissue is not completely healthy prior to the preparation and provisionalization process.

Prevention is very easy. First, don't prep teeth in the presence of unhealthy tissue! If the preps must be done in the presence of inflammation because of poor margins on existing restorations, then wait for the final impression until after the tissue is healthy.

Prior to luting the provisionals to the teeth, ensuring the excellence of the marginal integrity of the provisionals is critical to stopping, or at least minimizing marginal leakage.

The second step prior to luting is to use either a chlorhexidine gluconate scrub such as Concepsis from Ultradent or a gluteraldehyde application such as Gluma from Heraeus. Both solutions are antibacterial and if applied according to the manufacturer's directions will disinfect the surfaces of the preps and prevent the black line from forming.


Commenter's Profile Image Cody Calderwood
July 30th, 2013
If this does happen to you, the stain can be very tricky to remove. I, unfortunately, know this from experience. Don't panic though. The easiest way to get the black stain off the teeth is to gently scrub some superoxol on the teeth. It disappears instantly. Be careful with the gums though as it will burn them if you leave the superoxol on the gingiva too long.
Commenter's Profile Image Mark Olson
July 31st, 2013
Even safer, use peroxide in a scrub tip (yellow) and monoject syringe and scrub into prep surface
Commenter's Profile Image David Slaughter
August 8th, 2013
Ensuring margins are on enamel--not cementum as I suspect in this case, will provide an adequate bond to prevent leakage. I tell the dental students who shadow me to treat different structures independently. Address the gingival issues first, then restore the tooth. Don't try to cover a gum issue (like recession or exposed cementum) with a tooth borne restoration.
Commenter's Profile Image Henry Ramirez Dds
August 16th, 2013
i thought chlor hex was a soap and compromised bonding
Commenter's Profile Image Henry Ramirez Dds
August 16th, 2013
i thought chlor hex was a soap and compromised bond strength
Commenter's Profile Image DR Derry Rogers
August 16th, 2013
The position of the bacterial contamination is indicative of tensile forces acting on the Incisal edges flexing the labial gingival zones open hence allowing the ingress of the bacteria The same load issues will apply to the permanents if the provisional shapes and lingual inclines are followed identically Too steep an incline on the lingual locking in the lower anterior s can lead to this issue
Commenter's Profile Image Michael Ogden
August 17th, 2013
Actually, the worst of the gingival issues appear to be due to inadequate gingival embrasures in the temps. And no, Concepsis isn't a soap as such. It's a surfactant and actually promotes contact between the tooth surface and the phosphoric acid etch. And yes, plain peroxide is safe and effective on the stain. If you're using an iron-containing anticoagulant like ferric sulfate (Astrigident), you can expect this kind of staining. Try something like Tissue Goo instead.
Commenter's Profile Image Marco Brindis
August 19th, 2013
I've had this problem many times. I stop having the problem when I quit using ferric sulfate (Viscostat) for the final impression. I start using instead Aluminum Chloride (Viscostat Clear or Hemodent). I haven't had that kind of pigmentation ever since.
Commenter's Profile Image Cary Dunne
October 8th, 2013
It usually helps to rinse twice daily with chlorhexidine for week before doing the preps to cut down the preexisting inflammation as much as possible. It work really good for the tissue after the preps too, but the temps look bad pretty quickly.
Commenter's Profile Image Mel Musolf
June 4th, 2014
I have a few patients that have bonded or cemented veneers already in place with slight discoloration under the margin of the restoration. Any advice on how to treat the portion of the bond failure without a new veneer?
Commenter's Profile Image Steve Ratcliff
June 4th, 2014
If the stain is only at the margins and not underneath the restorations try using vital bleaching with with ever take home product and custom bleaching tray system you are using. That often removes all of the discoloration.
Commenter's Profile Image Mitchell K.
July 13th, 2016
Chlorehexidine prior to bonding I believe has shown to increase bond strength. I have a new patient with 20 year old veneers tooth #8/9, tooth #8 fractured incisal edge, with a black stain under the gingival margins and extremely red inflammed tissue. I would like to give him a chlorehexidine rinse that doesn't stain the teeth but I cant think of it as the moment. Does anyone know the name of the rinse? I am going to have him use the rinse for 2 weeks BID and reassess the tissue prior to new veneers. My other thought is that it is a biologic width issue and will sound the bone if it is still red and inflammed in two weeks. thank you.